Back in April I bought an HTC Nexus One (from Google). Last week, I dropped the phone for the first time, and the screen cracked. Having dropped a few phones over the years, I was surprised to not get at least one "free" drop without damage.
I then did a google search on "Nexus One screen cracked" and found pages of hits. There's even a youtube video showing just how delicate the screen is.
The HTC Desire has the same screen. You might want to read this set of posts
before you make your decision.
Now, all the Iphone users I know tell me they have dropped their Iphones lots of times, and not one has had a screen crack.
I've ordered a screen replacement kit (2400baht) and will be trying that shortly. I also bought a jelly plastic protective wrap for the phone, so maybe next time I drop it, it will survive.